Viruses are obligate cellular parasites and rely extensively on hijacking host cellular metabolic machinery for their replication. Meanwhile, virus infection of host cells is recognized by innate pattern recognition receptors that activate cascades of signal transduction pathways leading to production of type I interferons (IFN) and pro-inflammatory cytokines that orchestrate the elimination of the viruses. There is a need to quantitatively monitor viral activation of host cell beta-interferon (IFN-β) gene expression. As shown in FIG. 1, the present invention incorporates, in part, a HEK293-derived reporter cell line expressing a firefly luciferase gene under the control of a human IFN-β promoter (293TLR3/IFNβluc cells). Upon infection, viral genomic RNA and RNA replicative intermediates are recognized by endosomal TLR3 and cytoplasmic RLRs, respectively, and activates signaling cascades resulting in activation of three transcription factors (ATF2/c-Jun, NFκB, IRF3/IRF7), which cooperatively active IFN-β gene (or IFN-β promoter-driven Luc reporter gene) expression.
Unlike the traditional high throughput antiviral assays that measure either the reduction of viral components/yields or cytopathic effect, there is a need to have an assay which provides a direct measure of the virus-induced host cellular innate immune response. Hence, the assay allows for identification of compounds that inhibit virus infection.